Get memory data in Java

Question

I have the following C# code:

  int num = Convert.ToInt32(this.Memory.ReadInt(
        this.Memory.BaseAddress() + 0x80f0cc, new int[] { 12, 0x6c5c }));

This reads the data from the memory and gives me the integer value.

Is that somehow possible to achieve in Java? I've tried searching online but couldn't get anything.

score 1 · Answer 1 · answered Feb 02 '15 at 13:33

No, Java is specifically designed to disallow that... but...

It's not officially supported (and how/whether or not it works likely varies between JVM implementations), but the class sun.misc.Unsafe allows one to do stuff that you're normally not supposed to be able to do. See this article.

Excerpt:

@Test
public void testCopy() throws Exception {
    long address = unsafe.allocateMemory(4L);
    unsafe.putInt(address, 100);
    long otherAddress = unsafe.allocateMemory(4L);
    unsafe.copyMemory(address, otherAddress, 4L);
    assertEquals(100, unsafe.getInt(otherAddress));
}

The unsafe.getInt(otherAddress) call may be the closest thing you can achieve in pure Java.

There was a survey in 2014 about whether or not Unsafe should gain official support, but I'm not sure what (if anything) came of that.

If you allocate a memory via the unsafe.allocateMemory, don't forget to call `unsafe.freeMemory` when you finish your work with that memory. Otherwise you will create a memory leak. — Marian Spanik, Feb 02 '15 at 14:22

score 0 · Answer 2 · answered Feb 02 '15 at 13:28

0

No. It is not possible to access native memory with pure Java code. You can use JNA or JNI to link to native libraries, and they can access arbitrary memory but Java itself runs in a virtual machine and does not allow you to access memory explicitly inside or outside of the virtual machine.

answered Feb 02 '15 at 13:28

Elliott Frisch

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Thanks for you answer. Could you name any JNA library I can use with Java to achieve that ? – Makky Feb 02 '15 at 13:30
Any native library that allows you to access native memory. For example, your C# code above. – Elliott Frisch Feb 02 '15 at 13:33

score 0 · Answer 3 · edited Feb 02 '15 at 14:09

0

You could try going over to Project Kenai and having a look at the API and their examples:

Project Kenai

I also found an example for someone else who was trying to do something similar. Hope it helps.

Example

edited Feb 02 '15 at 14:09

Daniel Kelley

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answered Feb 02 '15 at 13:30

Gaz

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score 0 · Answer 4 · edited May 23 '17 at 12:28

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Makky, you can look at the old reply about memory management in java. He describes why you can not do this.

edited May 23 '17 at 12:28

Community

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answered Feb 02 '15 at 13:36

lonesomecodeboy

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Get memory data in Java

4 Answers4